/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.test.util;

import org.hamcrest.Matcher;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.xml.sax.InputSource;
import org.xmlunit.builder.DiffBuilder;
import org.xmlunit.diff.DefaultNodeMatcher;
import org.xmlunit.diff.Diff;
import org.xmlunit.diff.ElementSelectors;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Source;
import javax.xml.transform.dom.DOMSource;
import java.io.StringReader;
import java.util.Map;

import static org.hamcrest.MatcherAssert.assertThat;

/**
 * A helper class for assertions on XML content.
 *
 * @author Rossen Stoyanchev
 * @since 3.2
 */
public class XmlExpectationsHelper {

    /**
     * Parse the content as {@link Node} and apply a {@link Matcher}.
     */
    public void assertNode(String content, Matcher<? super Node> matcher) throws Exception {
        Document document = parseXmlString(content);
        assertThat("Body content", document, matcher);
    }

    private Document parseXmlString(String xml) throws Exception {
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        factory.setNamespaceAware(true);
        DocumentBuilder documentBuilder = factory.newDocumentBuilder();
        InputSource inputSource = new InputSource(new StringReader(xml));
        return documentBuilder.parse(inputSource);
    }

    /**
     * Parse the content as {@link DOMSource} and apply a {@link Matcher}.
     *
     * @see <a href="https://github.com/davidehringer/xml-matchers">xml-matchers</a>
     */
    public void assertSource(String content, Matcher<? super Source> matcher) throws Exception {
        Document document = parseXmlString(content);
        assertThat("Body content", new DOMSource(document), matcher);
    }

    /**
     * Parse the expected and actual content strings as XML and assert that the
     * two are "similar" -- i.e. they contain the same elements and attributes
     * regardless of order.
     * <p>Use of this method assumes the
     * <a href="https://github.com/xmlunit/xmlunit">XMLUnit</a> library is available.
     *
     * @param expected the expected XML content
     * @param actual   the actual XML content
     * @see org.springframework.test.web.servlet.result.MockMvcResultMatchers#xpath(String, Object...)
     * @see org.springframework.test.web.servlet.result.MockMvcResultMatchers#xpath(String, Map, Object...)
     */
    public void assertXmlEqual(String expected, String actual) throws Exception {
        XmlUnitDiff diff = new XmlUnitDiff(expected, actual);
        if (diff.hasDifferences()) {
            AssertionErrors.fail("Body content " + diff.toString());
        }
    }


    /**
     * Inner class to prevent hard dependency on XML Unit.
     */
    private static class XmlUnitDiff {

        private final Diff diff;


        XmlUnitDiff(String expected, String actual) {
            this.diff = DiffBuilder.compare(expected).withTest(actual)
                    .withNodeMatcher(new DefaultNodeMatcher(ElementSelectors.byNameAndText))
                    .ignoreWhitespace().ignoreComments()
                    .checkForSimilar()
                    .build();
        }


        public boolean hasDifferences() {
            return this.diff.hasDifferences();
        }

        @Override
        public String toString() {
            return this.diff.toString();
        }

    }

}
